I went way cheap on my cross ram. Just got some plastic plugs from McMaster Carr and submerged a few in gas for a few days. Found a couple that didn't warp and melt. Then I drilled a few holes in the intake and siliconed the plugs in there.

I've "sneezed" a couple times. Nothing major. Everytime, it pops those things out! I either find them or replace them with others that I keep in the glovebox! I've got about $7 invested in this!